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Cutting A Post Tension Slab 1

TBCENG

Structural
May 28, 2024
2
I am working on a home remodel where I will potentially have to cut into a post tension slab in order to place a new footing. Is there any issue in cutting the tendons to add this footing and then re-tensioning them once the new footing is set?
 
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I am working on a home remodel where I will potentially have to cut into a post tension slab in order to place a new footing. Is there any issue in cutting the tendons to add this footing and then re-tensioning them once the new footing is set?
Given you are in the US and it is a house slab I am going to assume it is UNbonded PT.

Where is the new footing to be placed in relation to the existing PT anchorages?

If it is remote from the PT anchorages - say more than 3 or 4 feet away - you may not have to cut the tendon/s, just work around it. Use GPR to locate the tendon/s, carefullu concrete chip the slab to create the necessary opening for the new footing (do NOT hit the tendon), then add your additional footing rebar, then place concrete to match the existing slab FLL.

If the new footing is close to the slab edge/PT anchorages, then concrete chipping to create the opening for the footing is a safety concern and best for the tendon to be de-tensioned first, then do the new footing excavation, splice the tendon with new short strand segment and splice chuck in an PVC tube, place new footing rebar, new concrete to footing, then re-stress the tendon.

The is This type of work is not usually carried out by a home building contractor. Call a local PT contractor - with experience!
 

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